Reddish Dust and Ice Migration Darken Saturn’s Moon Iapetus

These two global images of Iapetus show the extreme brightness dichotomy on the surface of this peculiar Saturnian moon.

New views of Saturn’s moon Iapetus accompany papers that detail how reddish dust swept up on the moon’s orbit around Saturn and migrating ice can explain the bizarre, yin-yang-patterned surface.

The papers, led by Cassini scientists Tilmann Denk and John Spencer, appeared online in the journal Science on Dec. 10, 2009.

The new image in the left-hand panel of Global View of Iapetus' Dichotomy shows the most nearly complete view to date of Iapetus’ charcoal-dark leading hemisphere. The right-hand panel, which had been released previously, shows the trailing hemisphere, where wide swaths are covered by bright ice. The new three-panel image Color Dichotomy on Iapetus uses false-color views in increasing levels of contrast to reveal the reddish dust that overlays the bright-dark pattern. Minimal enhancement was applied to the left panel, with increasing contrast added to the middle and right-hand images.

Three different false-color views of Saturn's moon Iapetus show the boundary of the global 'color dichotomy' on the hemisphere of this moon facing away from Saturn.